1. Field of the Invention
The present invention relates to a connector provided with built-in through capacitors for eliminating noise, and more specifically to a connector provided with built-in through capacitors resistant against thermal stress caused by soldering, for instance.
2. Description of the Prior Art
An example of prior-art connectors with built-in through capacitors is disclosed in Japanese Published Unexamined (Kokai) Utility Model Application No. 59-27022, as shown in FIGS. 1 to 4. The prior-art connector comprises a connector housing 100 made of a synthetic resin and formed with an inner partition 110, a shield casing 300 made of a metal and used as shielding plates and a grounding plate, a plurality of through capacitors 400 fitted to through holes 310 formed in the shield casing 300, and a plurality of connector pins 200 each passing through the partition 110 and the through capacitor 400, as depicted in FIGS. 1 and 2. The through capacitor 400 is composed of an outer cylindrical electrode 410 fixed to the shield casing 300 by solder 500, an inner cylindrical electrode 420 fixed to the connector pin 200 by solder 510, and a dielectric material 430 disposed between the outer and inner cylindrical electrodes 410 and 420. These through capacitors 400 serve to ground noise superimposed upon signals transmitted through the connector pins 200, that is, to minimize noise from being passed through the connector.
In the prior-art connector with built-in capacitors, however, since the connector housing 100 (i.e. the inner partition 110) for supporting the connector pins 200 is made of a synthetic resin, but the shield casing 300 for shielding the connector housing 100 and the connector pins 200 is made of a metal, the thermal expansion coefficient of the resin housing 100 is larger than that of the metallic shield casing 300. Therefore, there exists no problem at the normal temperature, because no thermal stress is generated in the connector; that is, the central axis CL.sub.1 of the housing inner partition 110 matches that CL.sub.2 of the through capacitor 400 as shown in FIG. 4(A). At a higher temperature, in particular the soldering process, a thermal stress is generated in the connector. That is, the central axis CL.sub.1 of the housing partition 110 is offset or dislocated away from that CL.sub.2 of the through capacitor 400 due to a difference in thermal expansion coefficient between the resin and metal as shown in FIG. 4(B). There exists a problem in that a thermal stress is inevitably generated in the solder 500 or 510 and the through capacitors 400 so that cracks are easily produced thereat during the soldering process.
To overcome the above-mentioned problem, although it is possible to render the differences in the thermal expansion coefficient between the resin housing and the metallic shield casing as small as possible under due consideration of the molding material and molding process even with these countermeasures it is difficult to obtain a satisfactory practical effect.